Products obtained from the hydrogenation of lignin in the presence of suitable catalysts



Patented Feb. "I, 1939 Qumran STATES PATENT OFFICE rnoooo'rs 'OBTAINED mo GENATION OF LIGNIN IN or SUITABLE ca'mmzs'rs Earl C. Sherrard and Elwin E. Wis, assignors to Henry A.

rotary of Agriculture America (his successors in oflice) No Drawing. Application May 10, 1938,

Serial No. 207,175

8 Claims. (Cl. 260-4311) (Granted under the act of March 3, 1883, as amended April 30, 1928; 370 0. G. 157) garlic solvent for 11 'ligno-ceilulose compl acid present in stances forme action, or by acidic be added. The lignin isolate water insoluble and m bohydrates by concen pouring the concentr This lignin, when wash is then ready for hydrogenation.

Our product may be pr wood or lignin-containing plan be hydrogenated may of the well-known soda, pulping proces neous plants acids or bases, by solvents, or by use 0 drochloric acid met This application is madev under the act of March 3, 1883, as amended by the act of April 30, 1928, and the invention herein described and claimed, if patented, may be manufactured and used by or fonthe Government of the United States of America for governmental purposes, without the payment to us of any royalty thereon. Our invention relates to the total product or products obtained from the hydrogenation of lignin in the presence of suitable catalysts such as copper chromium oxide, nickel, platinum, etc.,

at high pressures under controlled temperatures.

. The product consists of a mixture of methanol and high-boiling hydrogenated products, the hy- 15 drogenated products varying according to the conditions imposed or the catalyst used. This product maybe fractionated into components ranging from methylpalcohol to a high-melting product having possibilities as a plastic.

6 The principal object of our invention is the conversion of lignin waste into useful products. Lignin waste is available from various pulping processes, such as the sulphite, sulphate, soda and nitric acid processes, and may be converted,

2 after suitable pretreatment, into new and useful products by hydrogenation. Lignin is available in the residue remaining after the removal of cellulose from .wood or plant material by means of dilute acid at elevated pressures and temperatures as, for, examp1e,'in'the process of convertingwood and plant products into sugars or alcohol, or after treatment-with concentrated acid at lower temperatures and pressures. r-

Lignin obtained ircm wood or other lignin-con taining materials by organic solvents-such alfcohols as methyl, ethyl, butyl alcohols, and compounds with alcoholic groups such as ethylene glycol and the others '0! ethylene glycol, such as dozen-containing small amounts of acid or base or organic acids or bases, is also suitable for production oI-theseproducts. Other objects will appear I from the following description of the embodiments of the invention. In the manufacture of pulp from wood, or other 5 lignin-containing material, the lignin is con- 4.

.verted into a solubleproduct. The amount of lignin waste iromthese processes is approximately one-fourth of the dry weight of the starting material. The lignin may be removed from so ,lution by precipitation by various well-known methods'as an insoluble salt. This insoluble material, after purification, is suitable for the preparation of this hydrogenated material. I Other pulping processes are now in the process of development involving the use of an 'or- I M THE HYDRO- THE PRESENCE Harris, Madison, Wallace as Sected States of gnin. In this process the ex is broken either by the al to be pulped, by y d during the'pulping re- "or basic substances which may d in this manner is ay be separated from carq trating the solution and ted solution into water. ed with water and dried,

epared from ts. The lignin to be obtained as a sulphate, or H sulphite al from wood or ligents containing use of acidic or basic organic f the suiphuric'or fuming hyhods from wood or ligneous ses, by remov with organic solv ss consists of the purification of lignin ce by the removal of sugars, inornd impurities by selectively dislignin or the impurities. 4 The ed or suspended in a solvent temperatures and in the presence monometliyl other glycol ethers, lcyclohexanoland placed in e bomb, tested to 10,000 pounds grams of catalyst such as xide for each 100 grams or der 500 to 5000 pounds per is introduced, The bomb h 0 to 350 C. for several J aterial is then removed from the riiuged to recover the catalyst. formed by splitting 03 of methand the solvent are then ethoxyl groups of the d into methyl alcohol and can cunts from the solhighest yield oh- 5 to 20 percent of whichis a viscous colorless liquid,

into ,several colorless comat" to C. identified as parap II, boiling at to identified as 4- The. residue, can be fractionatedcomponent" I, boiling. and 1 mm. pressure, cyclohexanol; component C. and 1. mm. pressure,

1,2-dihydroxylcyclohexane; HI, boiling at to C. and 1 mm. pressure,

identified as 3=P-hyd xycyclohexylpropanol-1;

i and a component IV, having the empirical forcontents were fractionated into mula CrsHsaOa and distilling above 150 C. and 1mm. pressure, and solidifying into a hard, vitreous mass. Components I, II, III, and IV are unknown compounds which have never been prepared or described before.

When the same conditions in respect to solvent, pressure, temperature, and material were fol-' lowed, except that nickel was used as a catalyst,

ucts from the hydrogenation were metha viscous liquid difiering from that obtained when copper chromium oxide was used hydrogenation was incomplete. viscous liquid retains manyof the properties of therfiowing plastic.

The following examples serve to illustrate the conditions for preparing our product:

Example 1.-One hundred grams of dry, acidfree purified lignin isolated from wood by the action of methanol (containing hydrochloric acid) was dissolved in dry, constant boiling, 1,4 dioxan and placed in a bomb with 25 grams of copper chromium oxide catalyst. Then hydrogen, under 3000 pounds per square inch pres-, sure was introduced. The bomb was placed in a shaking device and heated at 250 C. for 8 hours. The material was then removed from the bomb and centrifuged to recover the catalyst. The

water-dioxan mixture, p-n-propylcyclohexanol, 4-n-propyl 1,2-dihydroxycyclohexane, ,3 p-hy; droxycyclohexyl propanol-l, and a product having the composition CmHaaOs boiling above 150 C. at 1 mm. pressure.

Example 2.0ne.hundred grams of dry, acidfree, purified lignin isolated from wood by the action of methanol containing an acid was dissolved in dry, constant boiling, 1,4 dioxan and placed in a bomb with grams of Raney nickel catalyst. Then hydrogen, under 2000 pounds per square inch pressure, was introduced. The bomb was placed in a shaking device and heated to 200 C. for 8 hours. The material was then removed from the bomb and centrifuged to recover the catalyst. The contents were fractionated into methyl alcohol, water-dioxan mixture, dioxan (the solvent), and a viscous brown semisolid which became a hard vitreous solid on heatinc.

The methanol prepared in this manner is of very high quality and satisfactory. for all purposes for which methanol is used. a

Component I, parapropylcyclohexanol, is valuable as a solvent for organic gums and resins, nitrocellulose, and oils such as are used in lacquers. It is a solvent for lignin and maybe used as a solvent for hydrogenation of lignin. It is also valuable as a wood preservative. being about equal to creosote in toxicity.

Components II and III are viscous liquids which solidify on long standing and are valuable as plasticizers for the makingof lignin and phenol formaldehyde plastics.

Component IV is a hard resin with properties that make it valuable for usein lacquers, either alone or in conjunction with nitrocellulose or cellulose acetate. compounded with other mate-' rials or alone it forms moldable plastics. Its strength properties and water resistance make liquid medium inert to methyl alcohol,

amacss this material valuable as a cement or adhesive for wood, paper, metal, etc.

Having thus described our invention, what we claim for Letters Patent is:

1. A product consisting of a mixture of monohydroxy cyclohexyl n-propans, monohydroxy cyclohexyl n-propano polyhydroxy cyclohexyl n-propans and polyhydroxy cyclohexyl n-propanols resulting from thehydrogenation of ligmin in the presence ofsuitable, catalysts at a temperature not exceeding 250 C. and operating pressure ranging from, 3,500-6,000 pounds. 1

2. A crystalline product, 3-p-hydroxycyclohexyl-propanol-l, having an empirical formula CBH1802 and a boil n point of 125 to 129 C. at 1 mm. pressure.

3. A vitreous product obtained by the hydrogenation of lignin, and having the empirical formula c18H3303 and a boiling point above 150, C. at 1 mm. pressure.

4. A process of converting lignin into methyl alcohol, which comprises suspending lignin in a the action of hydrogen, the while subjecting the lignin to the action of hydrogen in the presence of copper chromiurn' oxide at substantially 250 .C. and pressure greater than 2,000 pounds for such time as to assure completion of the hydrogenation reaction, thence removal of the mixture from the container, thence recovery of the catalyst, as by centrifuging, and thence separation of the methyl alcohol from the solvent medium and fractionation.

5. A process of converting lignin into parapropylcyclohexanol, 4-propyl 1,2-dihydrcxycyclohexane, 3-parahydroxycyc1ohexylpropanol-1, and a high-boiling product having the empirical formula CmI-InOawhich consists of treating lignin to the action of hydrogen and a suitable catalyst consisting 01. copper chromium oxide at high temperatures and pressures for such time as to assure completion of the hydrogenation reaction, thence removal of the mixture from the container, thence recovery of the catalyst as by centrifuging, and thence separation of the parapropylcyclohexanol, 4-propyl 1,2-dihydroxycyclohexane, S-parahydroxycyclohexyl propanol-1,

and the high-boiling product boiling above 150 *C. at 1 mm. pressure.

6. A process of converting lignin into methanol and a fast-flowing thermosetting plastic material, which comprises suspending lignin in aliquid medium inert to the action of hydrogen, the while subjecting the lignin to the action of hydrogen in the presence of nickel at substantially 250 C. and pressure greater than 2,000 pounds for such a time as to assure completion of the hydrogenation reaction, thence removal of the mixture from the container, thence recovery of the catalyst as by centrifuging, and thence separation of the product from methyl alcohol and the mediunr by fractional distillation.

'7. A fast-flowing thermosettlng plastic material resulting from the hydrogenation of lignin with nickel catalyst;

81 A fast flowing transparent thermoplastic material resulting from the hydrogenation of lignin with copper'chromium oxide catalyst.

o. SHERRARD.

other reaction products by 

